1. Field of Invention
The present invention relates to a semiconductor device. More particularly, the present invention relates to a memory device.
2. Description of Related Art
Non-volatile memory is currently used inside many types of electronic devices for holding structural data, programming data and other randomly access transient data. One type of non-volatile memory that can be repeatedly access is called flash memory. In fact, flash memory is an electrically erasable programmable read only memory (EEPROM) device that allows multiple data writing, reading and erasing operations. In addition, the stored data will be retained even after power to the device is removed. With these advantages, it has been broadly applied in personal computer and electronic equipment.
Conventionally, the memory device having a plurality of memory cell arranged in an array is constructed by several word lines parallel to each other. Furthermore, as shown in FIG. 3, at the boundary of the memory region where the functional word lines 302a are located, at least one dummy word line 302b is disposed directly aside the functional word lines 302a for the purpose of increasing the exposure uniformity of the lithography process. However, the existence of the dummy word line 302b aside the functional word lines 302a in the memory region would lead to coupling effect between the dummy word line 302b and the nearest functional word line 302a′. the coupling effect between the dummy word line 302b and the nearest functional word line 302a′ leads to differentiating the performance of the nearest functional word line 302a′ from the performance of other functional word lines 302a in the memory region. Therefore, the performances of the memory cells in the memory are not equivalent.